Construction begins on three new roundabouts in Puget Sound area

Roundabouts will improve traffic flow on SR 92 near Lake Stevens and at busy I-90 ramps near Issaquah

BELLEVUE – Drivers can look forward to smoother sailing at three busy intersections when construction is completed this fall on new roundabouts.

On Monday, June 10, the Washington State Department of Transportation will begin building a roundabout near the Interstate 90 on- and off-ramps at West Lake Sammamish Parkway in Issaquah. The crews from contractor Graham-Marshbank JV will also begin work on two new roundabouts on State Route 92 near Lake Stevens. One roundabout is located at 99th Avenue Northeast. The second is less than a mile east at 113th Avenue Northeast.

“These roundabouts will make it safer and easier for drivers to enter or exit the highways,” said Janice Fahning WSDOT project engineer. “All of these intersections have experienced plenty of collisions. The traffic volumes are increasing as well. The roundabouts will help move traffic more efficiently and reduce collisions.”

Roundabout benefits Roundabouts reduced injury crashes by 75 percent at intersections where stop signs or signals were previously used, according to a study by the Insurance Institute for Highway Safety. Roundabouts also achieve a 37 percent reduction in overall collisions.

The I-90 to West Lake Sammamish Parkway intersection was the site of 41 collisions from 2006-2010. At SR 92, the intersections at 99th Avenue Northeast and 113th Avenue Northeast had a combined 42 collisions from 2006-2010.

Roundabouts also improve traffic flow because they promote the continuous movement of traffic. Studies by the Federal Highway Administration have shown a 30-50 percent increase in traffic capacity compared to traditional intersections.

Lane closure details

I-90 on- and off-ramp roundabout

Drivers can expect traffic shifts, lane and ramp closures. Most of the work will occur Monday through Thursday nights.

SR 92 roundabouts at 99th and 113th avenues Northeast

The work at these intersections will require nighttime lane closures with flagging Monday through Thursday nights.

Drivers should also plan on a full closure through this section of SR 92 in mid-August when the roundabouts are put into their final configurations. That closure could last up to nine days. Drivers will follow a signed detour.